Frequency of micronuclei induced in cultured lymphocytes by highly toxic organochlorine congeners.

Our human bodies have already been contaminated with various chemicals including highly toxic organochlorine compounds such as 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD), 2, 3, 4, 7, 8-pentachlorodibenzofuran (PenCDF) and 3, 4, 5, 3', 4'-pentachlorobiphenyl (PenCB). In this study, in order to evaluate the genotoxicity of these three chemicals, we examined their effects on the induction of micronuclei, which has frequently been utilized as indicator of biological and genetic damage due to exposure to carcinogens or mutagens, in cultured human lymphocytes in the absence or presence of alpha-naphthoflavone (ANF) and the following results were obtained. 1)4 x 10(-5) M ANF alone significantly enhanced the frequency of micronuclei and the combination of ANF and either of TCDD, PenCDF or PenCB seemed to be additive as micronuclei inducers. 2) TCDD, PenCDF and PenCB significantly increased the frequency of micronuclei with almost the same dose-dependent manner in terms of the concentration of TCDD toxic equivalent. 3) TCDD, PenCDF and PenCB were considered to be very potent inducers of micronuclei, because their values of 50% effective concentration in micronuclei enhancement were around only 10 times higher concentration than that in healthy people, namely, 70ppt as TCDD. Consequently, the respective TCDD toxic equivalency factors of 0.5 and 0.2 for PenCDF and PenCB seemed to be reasonable so far as the induction of micronuclei was employed as an indicator of their genotoxic potency.(ABSTRACT TRUNCATED AT 250 WORDS)